(function (win, lib) {
    const doc = win.document;
    const docEl = doc.documentElement;
    let metaEl = doc.querySelector('meta[name="viewport"]');
    const flexibleEl = doc.querySelector('meta[name="flexible"]');
    let dpr = 0;
    let scale = 0;
    let tid;
    const flexible = lib.flexible || (lib.flexible = {});

    if (metaEl) {
        // console.warn('将根据已有的meta标签来设置缩放比例');
        const match = metaEl
            .getAttribute('content')
        // eslint-disable-next-line no-useless-escape
            .match(/initial\-scale=([\d\.]+)/);
        if (match) {
            scale = parseFloat(match[1]);
            dpr = parseInt(1 / scale);
        }
    } else if (flexibleEl) {
        const content = flexibleEl.getAttribute('content');
        if (content) {
            // eslint-disable-next-line no-useless-escape
            const initialDpr = content.match(/initial\-dpr=([\d\.]+)/);
            // eslint-disable-next-line no-useless-escape
            const maximumDpr = content.match(/maximum\-dpr=([\d\.]+)/);
            if (initialDpr) {
                dpr = parseFloat(initialDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));
            }
            if (maximumDpr) {
                dpr = parseFloat(maximumDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));
            }
        }
    }

    if (!dpr && !scale) {
    // eslint-disable-next-line no-unused-vars
        const isAndroid = win.navigator.appVersion.match(/android/gi);
        const isIPhone = win.navigator.appVersion.match(/iphone/gi);
        const { devicePixelRatio } = win;
        if (isIPhone) {
            // iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
            if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
                dpr = 3;
            } else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
                dpr = 2;
            } else {
                dpr = 1;
            }
        } else {
            // 其他设备下，仍旧使用1倍的方案
            dpr = 1;
        }
        scale = 1 / dpr;
    }

    docEl.setAttribute('data-dpr', dpr);
    if (!metaEl) {
        metaEl = doc.createElement('meta');
        metaEl.setAttribute('name', 'viewport');
        metaEl.setAttribute(
            'content',
            `initial-scale=${
                scale
            }, maximum-scale=${
                scale
            }, minimum-scale=${
                scale
            }, user-scalable=no`,
        );
        if (docEl.firstElementChild) {
            docEl.firstElementChild.appendChild(metaEl);
        } else {
            const wrap = doc.createElement('div');
            wrap.appendChild(metaEl);
            doc.write(wrap.innerHTML);
        }
    }

    function refreshRem() {
        // let { width, height } = docEl.getBoundingClientRect();
        const { height } = docEl.getBoundingClientRect();
        // window.console.log('screen', `width:${width}, height: ${height}`);
        // const ratio = ((width / height) / (1920 / 1080)).toFixed(1);
        // window.console.log('ratio', ratio);
        // 最小1280px，最大适配3840px
        // 800 1080
        /* if (height / dpr < 800) {
            height = 800 * dpr;
        } else if (height / dpr > 1080) {
            height = 1080 * dpr;
        } */
        // 设置成24等份，设计稿时1920px的，这样1rem就是80px
        const rem = height / 20;
        docEl.style.fontSize = `${rem}px`;
        flexible.rem = win.rem = rem;
    }

    win.addEventListener(
        'resize',
        () => {
            clearTimeout(tid);
            tid = setTimeout(refreshRem, 300);
        },
        false,
    );
    win.addEventListener(
        'pageshow',
        (e) => {
            if (e.persisted) {
                clearTimeout(tid);
                tid = setTimeout(refreshRem, 300);
            }
        },
        false,
    );

    if (doc.readyState === 'complete') {
        doc.body.style.fontSize = `${12 * dpr}px`;
    } else {
        doc.addEventListener(
            'DOMContentLoaded',
            // eslint-disable-next-line no-unused-vars
            (e) => {
                doc.body.style.fontSize = `${12 * dpr}px`;
            },
            false,
        );
    }

    refreshRem();

    flexible.dpr = win.dpr = dpr;
    flexible.refreshRem = refreshRem;
    flexible.rem2px = function (d) {
        let val = parseFloat(d) * this.rem;
        if (typeof d === 'string' && d.match(/rem$/)) {
            val += 'px';
        }
        return val;
    };
    flexible.px2rem = function (d) {
        let val = parseFloat(d) / this.rem;
        if (typeof d === 'string' && d.match(/px$/)) {
            val += 'rem';
        }
        return val;
    };
}(window, window.lib || (window.lib = {})));
